In many diseases, for example, rheumatism, arthritis, osteoporosis, inflammatory colitis, immune deficiency syndrome, ichorrhemia, hepatitis, nephritis, ischemic diseases, insulin-dependent diabetes mellitus, arterial sclerosis, Parkinson's disease, Alzheimer's disease, and leukemia, for example, stimulation of interleukin-1β production, an inflammatory cytokine, is observed. This interleukin-1β serves to induce synthesis of an enzyme which is considered to take part in inflammation-like collagenase and PLA2 and, when intra-articularly injected to animals, causes multiarticular damage highly resembling rheumatoid arthritis. In a healthy body, on the other hand, the activity of interleukin-1β is controlled by interleukin-1 receptor, soluble interleukin-1 receptor and interleukin-1 receptor antagonist.
From research conducted using recombinant versions of these bioactivity-inhibiting substances, anti-interleukin-1β antibodies and anti-receptor antibodies against various disease models, interleukin-1β has been found to play an important role in the body, leading to an increasing potential of substances having interleukin-1β inhibitory activity as therapeutics for such diseases.
For example, immunosuppressors and steroids, which are used for the treatment of rheumatism, have been reported to inhibit production of interleukin-1β. Among compounds currently under development, KE298, a benzoylpropionic acid compound [The Japanese Society of Inflammation (11th), 1990], for example, has been reported to exhibit inhibitory activity against interleukin-1β production although it is an immunoregulator. Inhibitory activity against interleukin-1β production is also observed on a group of compounds which are called “COX-2 selective inhibitors”, for example, nimesulide as a phenoxysulfonanilide compound (DE 2333643), T-614 as a phenoxybenzopyran compound (U.S. Pat. No. 4,954,518), and tenidap (hydroxyindole compound) as a dual inhibitor (COX-1/5-LO).
Moreover, interleukin-1β production inhibitory activity is not the primary action or effect of any of these compounds so the inhibitory activity against interleukin-1β production is less than the primary action thereof.
More recently, increased synthetic research has been conducted emphasizing inhibitory activity against interleukin-1β production. Production inhibitors can be classified into (1) a group of compounds which inhibit the transfer process of an inflammatory signal to a cell nucleus and (2) another group of compounds which inhibit the enzyme ICE that functions in the processing of a precursor of interleukin-1β. Known examples of compounds presumed to have the former action 1) include SB203580 [Japanese Language Laid-Open (Kokai) Publication (PCT) No. HEI 7-503017], FRI67653 (Eur. J. Pharm., 327, 169–175, 1997), E-5090 (EP 376288), CGP47969A (Gastroenterology, 109, 812–828, 1995), hydroxyindole derivatives (Eur. J. Med. Chem. 31, 187–198, 1996), and triarylpyrrole derivatives (WO 9705878), while known examples of compounds presumed to have the latter action 2) include VE-13,045 which is a peptide compound (Cytokine, 8(5), 377–386, 1996).
None of these compounds, however, exhibits sufficient inhibitory activity against interleukin-1β production.
On the other hand, it is known that 5,6-diphenyl-pyridazine compounds exhibit analgesic and anti-inflammatory action (Eur. J. Med. Chem., 14, 53–60, 1979). Further, 6-phenylpyridazinones have been reported to be useful as cardio-active compounds (U.S. Pat. No. 4,404,203). Nothing has been reported, however, with respect to inhibitory activity of these pyridazine compounds against interleukin-1β production.
The present inventors previously reported in WO 99/44995 that high inhibitory activity against interleukin-1β production was observed on phenylpyridazine compounds. Recently, certain phenylpyridazine compounds having inhibitory activity against interleukin-1β production have been reported (JP 7-69894 A, WO 98/41511, WO 99/10331, WO 99/10332, WO 99/25697, WO 00/50408). These reported compounds, different in chemical structure from the compounds of the present invention, however.